Calcium is a natural element in the must, although in certain manufacturing processes calcium salts (calcium carbonate for acidity reduction) and other calcium-rich substances (casein for clarification) can be added. The solubility of calcium decreases with increasing alcohol content, easily reaching supersaturation. In these cases there is a risk of causing calcium tartrate precipitates (and in some cases calcium oxalate) during aging inside the bottle, since its formation is very slow. This problem is particularly relevant in white wines because of its visibility. The control of calcium levels makes it possible to force the precipitation of said crystals, and their subsequent filtration, as part of the manufacturing process.